Skip to Content. New geological evidence indicates the Grand Canyon may be so old that dinosaurs once lumbered along its rim, according to a study by researchers from the University of Colorado at Boulder and the California Institute of Technology. The team used a technique known as radiometric dating to show the Grand Canyon may have formed more than 55 million years ago, pushing back its assumed origins by 40 million to 50 million years. The researchers gathered evidence from rocks in the canyon and on surrounding plateaus that were deposited near sea level several hundred million years ago before the region uplifted and eroded to form the canyon. A paper on the subject will be published in the May issue of the Geological Society of America Bulletin.
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Buff Bulletin Board. Events Calendar. Search Enter the terms you wish to search for. Published: April 10, The National Science Foundation and Caltech funded the study.
During a flood, the increased volume of water can flow at a rate ofcubic feet per second cfs. Imaginebasketballs, each about the size of a cubic foot, barreling past you each second! The Colorado River flows through an Arid Climate. Mechanical weathering happens relatively quickly in arid regions. In more humid regions, plants cover the land and help slow erosion.
In arid climates, there is often very little soil, leaving bedrock exposed. The exposed rocks are more easily eroded by precipitation, daily fluctuations in surface temperature, and ice-wedging during winter months. Rivers flowing through arid landscapes can carve through rock more easily because the rock is exposed and weathered. The Grand Canyon is a dynamic place Weathering and erosion are ongoing processes.
If we were to visit Grand Canyon in another couple million years, how might it look? For one, it would be wider; we may not even be able to see across it anymore.
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As long as water from snow melt and rain continues to flow in these side drainages, erosion will continue. The rocks through which the river is currently downcutting are hard, crystalline igneous and metamorphic rocks, which are much stronger than the sedimentary rocks resting above them.
Because sea level 0 ft. Currently controlled by Glen Canyon Dam, the Colorado River through Grand Canyon no longer experiences dramatic changes in water volume throughout the year.
Prior to the construction of Glen Canyon Dam, the volume of flow of the Colorado River would decrease to as low as - cfs in late summer. Then, in late spring when snows in the Rocky Mountains were melting, the river would swell tocfs or more.
In the past, downcutting occurred during these spring floods because the flood waters could carry tremendous amounts of sediment and had the power to sweep huge rocks downstream.
The highest recorded pre-dam flow was aboutcfs in The highest recorded post-dam flow of just 92, cfs was in Much of Northern Arizona is dotted with cinder cones, lava domes and stratovolcanoes.
The San Francisco Volcanic Field, which contains at least cinder cones, covers 1, square miles. Standing at about the center of this vast volcanic field are the prominent San Francisco Peaks of Flagstaff, Arizona, remnants of a geologically young stratovolcano.
Cinder cones are also found near the western end of Grand Canyon, between Toroweap Valley and Hurricane fault. One such lava dam was over 2, feet high, reaching several hundred feet higher than Glen Canyon Dam does today. Because these dams were not particularly strong, they were probably very short lived. One thing we can be sure of is that the lava dams were removed by the erosive action of the Colorado River.
Evidence of huge outburst floods has been well documented in western Grand Canyon. Finally, aboutyears ago, volcanic eruptions came to an end, and the river was temporarily blocked for the last time.
Numerous normal faults cut across Grand Canyon. The most active faults in northwestern Arizona are the Hurricane and Toroweap faults, which cut across Grand Canyon near river miles and Significant offset can be observed along these faults, which have moved vertically between and feet in the past 2 million years.
Ruptured rock layers are also common in this stretch, offering evidence for the occurrence of major earthquakes. Learning more about these faults is exciting because they help scientists determine just how fast the Colorado River is downcutting. How old are Grand Canyon and the Colorado River? Landscapes are more difficult to date than rock formations.
Still, by looking at relationships between rock formations, scientists are able to determine ages of landscapes with some precision. Scientists have used this type of relative dating technique to narrow the age of the Colorado River and Grand Canyon.
Scientists know that the Colorado River carved Grand Canyon. The river is thus slightly older than the canyon, though the two are certainly close in age. Scientists have studied rock deposits along course of the present day Colorado River.
By looking at the type of sediments the deposits contain, scientists determine whether or not the rocks were deposited by the river.
Rocks deposited by the river are younger than the river, as the river needed to be around to deposit them. Rocks not deposited by the river are older than the river because the river was not yet there to drop them. When possible the scientists then date these rock deposits. The age of the river falls between the rocks determined to be older than the river and those determined to be younger.
Through this method, scientists have estimated an age for the river, and thus the canyon through which it flows, of million years. Hualapai Limestone 6 - 11 million years ago.
The Hualapai Limestone was deposited in a warm, shallow freshwater lake just west of the Grand Wash Cliffs. It does not contain any river sediments, therefore, the Colorado River was not flowing yet when the Hualapai Limestone was deposited.
The estimated age of the Hualapai Limestone is 6 million years.
It was obtained from the Fortification Basalt, a lava flow that is interbedded with the sediments. Sandy Point Basalt 4.
The river was therefore present and flowing before the basalt was deposited. The Sandy Point Basalt is 4. The quartz-rich sands and silts of the Bouse Formation are found in just three basins along the modern Colorado River.
Scientists believe that these sediments came from the Colorado River, though their precise depositional environment is debated.
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Some believe the Bouse Formation was deposited in an estuary, while others claim that deposition took place in a series of freshwater lakes fed by the Colorado. The water in both of these possible environments would have been from the Colorado River.
Therefore, the river was already flowing about 5 million years ago.
Imperial Formation 4. The Imperial Formation is composed of both marine and deltaic sediments, meaning that it was deposited at the mouth of a river on a delta that was sometimes covered by the sea.
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Colorado River sediments are found in this formation. In particular, the Imperial Formation contains microfossils from rock layers on the Colorado Plateau. The Colorado River, then, must have been carrying eroded rock materials from the Plateau to its mouth by 5 million years ago. It was this event that allowed for the establishment of the modern, through-flowing Colorado River.
Connecting the Colorado River of the Colorado Plateau with an outlet to the sea lowered the base level by about 5, feet 1, m. The base level is the lowest level to which a river can erode its bed.
Jun 01, The radioisotope methods, long touted as irrefutably dating the earth as countless millions of years old, have repeatedly failed to give reliable and meaningful absolute ages for Grand Canyon rocks. Irreconcilable disagreement within, and between, the methods is . The oldest rocks in the Grand Canyon are the Proterozoic Vishnu schist which was dated to about 2 billion years ago. This forms the base of the Grand Canyon rocks, about 25, feet high and composed of both sedimentary and metamorphic rocks. Uncertainties Of Dating The Grand Canyon I have noted that old-earth creationists believe that the Grand Canyon strata were formed over hundreds of millions of years and that the canyon itself was carved out in less than five million years.
The ultimate base level is sea level 0 ft. The introduction of this lower base level created the conditions necessary for incision through the Colorado Plateau to occur.
How did the Colorado River and Grand Canyon come to be? It is fairly easy to explain the formation of Grand Canyon through downcutting, weathering, and erosion. It is more difficult to explain just how the Colorado River came to be in its current location. We can think of the development of the Colorado River as a history book with many chapters.
The base of the Grand Canyon are Precambrian basement rocks. These were formed from flowing magma which cooled and hardened about billion years ago. In the table below, you can find the formation of Grand Canyon rock layers which date back to 2 billion years. As you can see, most of the rocks are sedimentary like shale, limestone and sandstone. Scientists have used this type of relative dating technique to narrow the age of the Colorado River and Grand Canyon. Scientists know that the Colorado River carved Grand Canyon. The river is thus slightly older than the canyon, though the two are certainly close in age. Overlying those rocks in the ordinary geologic record should be a thick sequence of Mesozoic rocks (about to 65 million years old), but rocks dating from the Mesozoic Era in the Grand Canyon have been entirely eroded away.
The most recent chapter is familiar, because it is the chapter that is visible today. But, there are a number of chapters missing.
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The plotlines of some of those missing chapters are heavily debated. There are a few chapters in the story that the majority of geologists agree upon. For one, evidence collected thus far suggests that the upper and lower reaches of the Colorado River are different ages. These are former sedimentary and volcanic strata that have been transformed by heat and pressure, possibly during the intense upheavals when the dry land was formed on Day 3 of Creation Week.
These were originally basalt lava flows several meters to tens of meters thick. In some outcrops pillow structures have been preserved, testimony to the basalt lavas having originally erupted and flowed under water onto the Creation Week ocean floor.
Metamorphic rocks are not always easy to date using radio-isotopes. Results obtained usually signify the "date" of the metamorphism, but they may also yield the "age" of the original volcanic or sedimentary rock. The "age" or "date" is calculated from the amount of the daughter isotope produced by radioactive decay of the parent isotope.
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In Grand Canyon, the "date" of metamorphism of the basalt lavas to form these Brahma amphibolites has been determined as Ma million years agobased on U-Pb dating of minerals in the overlying Vishnu Schist and underlying Rama Schist that formed during the metamorphism.
These included seven samples from a meter long and 2 meter wide amphibolite body outcropping just upstream from the mouth of Clear Creek at river mile 84 measured from Lees Ferry. All 27 samples were sent to two well-credentialed internationally-recognized, commercial laboratories for radioisotope analyses-potassium-argon K-Ar at a Canadian laboratory, and rubidium-strontium Rb-Srsamarium-neodymium Sm-N and lead-lead Pb-Pbat an Australian laboratory.
Both laboratories use standard, best-practice procedures on state-of-the-art equipment. The model K-Ar ages for each of the samples ranged from Furthermore, the seven samples from the small amphibolite unit near Clear Creek, which should all be the same age because they belong to the same metamorphosed basalt lava flow, yielded K-Ar model ages ranging from This includes two samples only 0.
The computer program Isoplot 6 was used to plot isochrons and calculate isochron ages from the other radioisotope analyses. Most people believe that when the different radioisotope dating methods are used on the same rock unit they all yield the same age.
However, the radioisotope dating of these Grand Canyon rocks clearly demonstrates that the disagreement, or isochron discordance, is pronounced. None of the obtained isochron "ages" corresponds to the "date" for any recognized event, neither the original lava eruptions nor the subsequent metamorphism.
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And the K-Ar model "ages" are so widely divergent from one another ranging from These discordant results could easily be dismissed as an isolated aberration, perhaps due to the uncertain effects of metamorphism and any subsequent alteration, especially during erosion and weathering.
However, they are confirmation of the repeated failure of all the radioisotope "dating" methods to successfully date Grand Canyon rocks. Yet the RATE research has uncovered much evidence, including the patterns of these discordances between the "dates" from the different radioisotope systems, 10 that radioisotope decay rates were accelerated in a global catastrophic event in the recent past.
Apr 10, The team used a technique known as radiometric dating to show the Grand Canyon may have formed more than 55 million years ago, pushing back its . Grand Canyon National Park Dating Rocks. Two major categories of geologic dating techniques exist: relative dating and absolute age determinations. The Age of Grand Canyon Rocks. Beginning with John Wesley Powell in the s, geologists have recognized three main Vishnu Basement Rocks. We. This principle is a key part of determining the relative age of a rock layer. The three main rock layer sets in the Grand Canyon are grouped based on position and common composition and 1) Metamorphic basement rocks, 2) The Precambrian Grand Canyon Supergroup, and 3) Paleozoic strata.
Because the different radioisotopes are dating the same geologic event, to have produced different "dates" has to mean that the parent radioisotopes have decayed at different rates over the same time period.
In other words, the decay of the parent radioisotopes was accelerated by different amounts, the decay of those yielding older "ages" the alpha-decayers having been accelerated more. Obviously, if radioisotope decay was accelerated, say during the Genesis Flood, then the radioisotope decay "clocks" could never be relied upon to "date" rocks as many millions of years old. To the contrary, the rocks could still only be a few thousand years old.